5 children on UC

Office discussion with 2 different opinions.
Client has 2 children pre April 2017 and one post 2017, so 2 included in UC claim.  Now expecting twins.  Opinion 1 is that one not included but second child is, the other that neither is included. 
thoughts please..

Confusion is probably because the government originally intended not to include either twin in such a case. However, the policy changed pretty quickly, and they would get a child element for the second twin.

Thanks Charles, trying to find link to updated regs but couldn’t, can anyone point me in the right direction? Thanks

Go to:
https://www.legislation.gov.uk/uksi/2013/376/contents
On the left-hand side is a link to the updated version of the Regs.

This provision is in para 2 of Schedule 12.